Pan type concrete mixers



Feb. 2, 1965 H. R. cowLEY 3,168,296

PAN TYPE CONCRETE MIXERS ffy/wa www af@ .BY s

Feb. 2, 1965 H. R. cowLEY l3,168,295

PAN TYPE CONCRETE MIXERS Filed May 15, 196s 4 sheets-sheet 2 Feb. 2,1965 Filed May 15, 1965 H. R. COWLEY PAN TYPE CONCRETEv MIXERS 4Sheets-Sheet 5 Feb. 2, 1965 H. R. cowLl-:Y

PAN TYPE CONCRETE MIxx-:Rs

4 Sheets-Sheet 4 Filed May 15, 1963 United States Patent 3,l63,,96 PANTYPE CGNCREZFIE MEXERS Harold Raymond Cowiey, Bath, Snmerset, England,as-

signer to Stnthert Pitt, Limited, Bath, Somerset, Engiand, a eerporatinnof the United Kingdom Fiied May i3, 1h63, Ser. Nn. 279,971 Claimspriority, application Great Britain, Mar. 8, 1963, 9,295/ 63 12 Claims.(Cl. 259-178) This invention relates to concrete mixers of the pan typewherein the shell of the mixer is in the form of a cylindricalopen-topped pan bounded by inner and outer circumferential verticalwalls and a bottom wall, providing an annular mixing chamber withinwhich paddles or blades circulate.

Hitherto concrete mixers of this type have sulfered from thedisadvantage that the mixing paddles have been driven by gearingsituated in vertical alignment with the shaft constituting the axisabout which the paddle arms revolve, and this has made maintenancediiiicult, due to the inaccessibility of the driving parts, and has alsonecessitated frequent cleaning of the mechanism, due to splashing fromthe incoming materials and also from the concrete being mixed. Thepresent invention overcomes these disadvantages by positioning thegearing outside and below the top edge of the mixing pan, so that it iswell clear of incoming materials, avoids splashing from the concretebeing mixed, and may be maintained without removal.

Furthermore, it is well known that pan type concrete mixers suffer fromthe disadvantage that, due to the continuous movement of the paddles orblades through the material, the blade supports are subjected toconsiderable wear and tear which results in deformation and subsequent`breakage thereof almost without warning. The operation of replacingthese supports is, particularly where the connecting brackets thereofare covered in hardened concrete, sometimes a diflicult task and resultsin a loss of time and output on the building or other site.

It is therefore further among the objects of the present invention toprovide a paddle or blade support assembly in which the problem of wearis considerably reduced or eliminated.

According to the present invention, a pan mixer of the type having astationary pan formed by inner and outer cylinders providing an annularmixing chamber within which paddles or blades circulate, has the paddlesor blades suspended through support assemblies from spider arms mountedto revolve about the central axis of the mixing pan and driven throughtransmission gearing by means preferably comprising a gear ring attachedto the v spider arms externally of the outer cylinder of the mixing pan.

In general, the spider arms are either secured to a shaft mounted torotate in bearings fixed in the inner cylinder, or they are rotatablysupported by bearings on a shaft fixed in the inner cylinder, and inboth cases the free ends of the spider arms project beyond the perimeterof the outer cylinder, the gear ring being secured to the outerextremity of the arms.

The mixing paddles or blades are caused to rotate by means of the gearring which meshes with a spur wheel fast on an output shaft of areduction gear box, driven by an electric motor `or other prime mover;both the prime mover and the gear box are positioned externally of thepan at a convenient level, the gear box having a vertically arrangedoutput shaft.

Secured to the spider arms at points at, or closely adjacent, theperimeter of the outer cylinder are the blade support asseinbiies towhich are attached the mixing 3,l68,296 Patented Feb. 2, 1965 HCSblades, or the scraper blades, or both the mixing and the scraperblades.

The outer or free ends of the spider arms, and the gear ring supportedtherefrom, are covered either by a guard plate or by a cover supportedwholly or partly from either the inner or outer cylinders, or from both.

A further feature of the invention is the provision of one or moreplough blades which are effective to move the material outwards from aposition adjacent the inner cylinder, where it is mixed less efficientlydue to the relatively small diameter of the pan at this point, to aposition where mixing is more eciently carried out.

A still further feature is that, in order to avoid shock and high peakloading generally due to the practice Of feeding materials into the panat one xed point, a feed chute is attached to a hub carrying the spiderarms so that it rotates therewith, the feed end of the chute beingarranged concentric with the axis of rotation of the spider anne, andthe discharge end thereof being arranged below the level of the spiderarms but above the working level of the material so that the materialsare fed directly into the mixing chamber and are distributed throughoutthe Ywhole or" the annulus thereof.

A still further feature of the present invention is that each bladesupport assembly comprises a supporting arm, a first bracket member, towhich the paddle or blade is attached, and which is fixed to one end ofthe supporting arm, a second bracket member xed to the other end of thesupporting arm for connection to its co-acting spider arm, a wearresistant sleeve which is split longitudinally surrounding thesupporting arm and extending between the iirst and second bracketmembers, and means for securing the split sleeve in position on thesupporting arm.

In a preferred arrangement the split sleeve is of tubular formation andthe means for securing the split sleeve in position on the supportingarm comprise semicircular projections formed on the bracket members anda locking key associated with one or both projections, the projectionsbeing arranged at to the split joint of the tube.

The present invention presents the advantage over existing arrangementsof improved accessibility for maintenance due to the fact that all thegearing is external to the shell of the mixer. Furthermore, the bearingsof the central vertical shaft are arranged so that they can be withdrawnwith their housings. The possibility of torsional oscillation is reducedbecause the number of rotating parts is small, and because the load fromthe mixing elements is applied close to the point of power input.

The invention is illustrated by way of example in the accompanyingdrawings in which,

FIGURE l is a plan view of a pan mixer according to the invention withthe guard plate or cover removed,

FIGURE 2 is a cross-section corresponding to FIG- URE 1,

FIGURE 3 is a perspective View, with some of the parts broken away forclarity, of a blade support assembly,

FIGURE 4 is a longitudinal section through the support assembly,

FIGURE 5 is a section on the line A-A of FIGURE 4, and

FIGURE 6 is a section on the line B-B of FIGURE 4.

Referring to FIGURES 1 and 2 of the drawings a concrete mixer of the pantype comprises an annular cylindrical mixing chamber l consisting of anouter cylinder 2, an inner cylinder 3 and a door or base 4. The outersurface of the inner cylinder 3, the inner surface of the outer cylinder2, and the inner surface of the floor or base 4, are fitted withrenewable lining plates.

The centre or dead space formed by the inner cylinder 3 contains acentral vertical shaft 5 which can rotate freely in bearings 6 and 7removably housed in shaft 5 in order to rotate with it. Alternatively,the shaft 5 may be fixed within the inner cylinder 3 and the hub 8arrangedto rotate freely onrbearings about the shaft.

The hub il has fixed thereto radially arranged spider arms 9 supportingat their free ends a-circumferential flange l0, each spider arm 9carrying one or more blade supporting assemblies indicated generally at11 to which are attached mixing blades l2 and/ or scraping blades 13which project downwards into the mixing chamber l.

A spur toothed gear wheel 14, which is built up from several identicaland interchangeable segments, is attached to the circumferential flangeit) of the spider. The gear wheel ltdmeshes with a spur toothed gearpinion l5 fixed to the vertical output shaft l5 of a worm or spur gearreduction box i7, the input shaft of which is driven by a prime mover18, for example, an electric or hydraulic motor, or a diesel engine.

The whole mixing pan is covered by a guard or cover i9 which may beconical or dome-shaped, and be in one or more parts. The guard or cover19 serves to enclose the mixing pan and in addition protects the gearingi4, which is located outside and below the top edge of the mixingchamber, in which position the gearing also evades any splashing fromthe concrete being mixed in the chamber.

The materials to be mixed are fed into the annular mixing chamber 1 bymeans of a feed chute 20 which is supported on the hub S by means ofbrackets 21 so that it rotates therewith. The inlet end 22 of the feedchute 2t) extends through the guard or cover 19 and is arrangedconcentric with the axis of rotation of the hub 3, whereas the discharge23 thereof is arranged at a position slightly above vthe working levelof the material in the mixing chamber. Thus, in use, the material isrfed to the mixing chamber in such manner that it is distributed aroundthe whole annulus of the mixing chamber and is not liable to enter intocontact with the spider arms, or the working parts of the mixer. VThisarrangement also avoids the disadvantage of known mixers, where thematerials are fed into the mixing chamber at one fixed point in thelannulus thereof, since it avoids the setting up shock loads on thedriving mechamsm.

The concrete is discharged from the mixing chamber 1 through one or moreopenings in the licor or base 4 thereof. The or each opening is sealedduring Va mixing process by means of a door 24 which lits flush with thepan bottom d. The or each door 24 may be of semi-circular or of fanshaped formation and is adapted to open radially about a verticallydisposed hinge pin 25, to a position indicated at 24a, under the actionof a ram 26 the piston rod 27 of which is connected to a link 28 fast onthe hinge pin 25.

Water for the mixing process is yadmitted to the mixing chamber, from ameter or measuring tank, via a pipe 29 fitted with nozzles, which pipeextends upwardly through the yinner cylinder 3 and either partially orcompletely circles the inner cylinder 3 in a position at or near theupper edge thereof.

Thus, in use, the materials to be mixedare passed into the mixingchamber1 through the feed chute 20 and are distributed throughout the whole ofthe annulus thereof, and the water to be used in the mixing operation ispassed into the chamber through the nozzles in the water pipe 29. Duringthis operation the blades l2 and i3 are caused to rotate to effectmixing. The mixing blades l2 serve to mix the material and the scraperblades i3, which are arranged adjacent the inner surface of the outercylinder 2, as well as effecting a Vcertain degree of mixing, serve tomove the material inwardly into the path of the mixing blades 12.

It has been found that when using mixing blades and scraper blades only,a certain amount of segregation of the material takes place because, ina mixer of this type i in which the inner wall of the mixing chamber isof relatively small diameter compared with the outer wall, the mixingblades nearest the axis of rotation has a much slower peripheral speedthan those nearer the outer wall. The result of this is that thematerials being mixed nearest the inner wall of the chamber aresubjected to less eflicient mixing action and consequently segregate.

In order to overcome this disadvantage, one or more plough blades 3l?,which are supported on spider arms 9 via support assemblies lli, arearranged adjacent the inner cylinder 3 to move the maximum amount ofmaterials outwards from the inner wall of the mixing chamber into thefaster, and therefore more eicient mixing zone of the chamber, and atthe same time serve to lift the materials and turn them over to obtain ablend with the materials which are directed inwardly by the scraperYblades 13 adjacent the outer wall of the mixing chamber.

Although the invention has been illustrated to show each of the blades,i.e. the mixing blades 12, or the scraper blades i3, or the ploughblades 3u, mounted on a separate spider arm 9, it will be understoodthat each spider arm may support any convenient number of bladesaccording to requirements.

Referring to FIGURES 3 to 6 of the drawings, each support assembly 11comprises a supporting arm 31 of circular cross-section, a first bracketmember 32, t-o which the paddle or blade 12, or 13 or 30 is attached,and which is fixed lat one end of the supporting arm 31, and a secondbracket member 33 fixed at the other end of the supporting arm 31. Thebracket 33 is provided with holes 33 to receive a hinge pin 33 by whichthe bracket 33 is adapted to be hingedly attached t-o one of the spiderarms 9.

A wear resistant tubular sleeve 34, which is ,of a hard or a hardenedmetal, and is split longitudinally to present two semi-circularsections, is provided to encase the supporting arm 31v and to extendbetween the two brackets 32 and 33.

The sleeve 34 is supported on the arm 31 in such manner that the jointsthereof lie perpendicular to the direction of movement of the arm sothat an unbroken Yarcuate lface of the sleeve is directed towards thematerial being mixed and takes the brunt of the wear caused byfiictional engagement with the material.

In order to hold the sleeve 3ft in position, the brackets .32 and 33 areformed respectively with semi-circular projections 35 and 36 which arearranged, in use, at 90 to the split joint of the sleeve 34.

'Ilo position the sleeve 34, one half section is placed against thesupporting arm 31 @and turned so that it is held in the projections 35and 36, the second half section is then placed on the top surface ofsupporting arm 31, and the whole sleeve is then turned through so thatthe split joint is at 90 to the projections 35 and 36. The sleeve isheld in this position by means of a locking key 37 which is passedthrough a slot formed in the projection 36 and into .a slot formed bynotches 38 provided in the ends of the two half sections of the sleeve34. The locking key 37 is secured in this position, by means of a bolt39, to a radially directed flange 40 formed on the projection 36adjacent the slot. Thus, it will be seen that the locking key 37prevents rotation and thus removal of the sleeve 34.

As will be seen from the drawing, the sleeve 34 is formed at each end,fand in two diametrically opposite positions, with notches 38 to provideslotsrfor receiving the locking key 3'7 in four diiferent positions. Thereason for this is that, as will be obvious, the lower end of thesleeve, and the leading face of the lower end of the sleeve, will besubjected to the most wear and it is a distinct advantage of the presentinvention that the wearing surface can be changed four times for eachVsleeve used. YThus, when the lirst wearing surface is Worn the Vsleeveis turned, by releasing the locking key 37, through 180 to present asecond wearing surface, and when the second surface is worn, as the twoends of the sleeve 34 are the same, the sleeve can be turned end-to-end,i.e. the lower end is placed y'at the top of the arm, and two furthersurfaces are presented as hereinbefore described.

Thus, it will be understood that a single sleeve used in the mannerdescribed provides virtually four diterent replacement sleeves.

I claim:

1. A pan type mixer comprising a stationary pan consisting of =an innercylinder, an outer cylinder and a base extending between said inner andouter Cylinders to present an annular mixing chamber, a plurality ofradially disposed spider arms mounted to revolve about the central axisof said mixing chamber, a plurality of supporting arms depending viahingedly mounted brackets from said spider arms into said mixingchamber, -a plurality of blades attached via xedly mounted brackets tosaid supporting arms and adapted to circulate in said mixing chamber onmovement of said spider arms, a wear resistant sleeve surrounding eachof said supporting arms and extending between said hingedly mountedbracket and said iixedly mounted bracket, and drive means for revolvingsaid spider arms about said central axis of said mixing chamber, saiddrive means including a gear ring fixed to the free ends of said spiderarms, and a prime mover arranged in driving relationship with said gearring via gearing, said gear ring, said prime mover and said gearing allbeing arranged wholly externally of said mixing chamber.

2. A pan type mixer as claimed in claim 1, in which said wear resistantsleeve is of tubular formation and is split longitudinally to presenttwo sleeve halves, and means are provided for securing said sleevehalves on said supporting arm.

3. A pan type mixer as claimed in claim 2, including semi-circularprojections provided on said hingedly mounted and xedly mounted bracketsfor receiving the ends of said sleeve halves.

4. A pan type mixer as claimed in claim 3, including locking means forpreventing rotation and thus removal of said sleeve halves, said meansconsisting of a locking key passing through a slot formed in one of saidsemi circular projections and into a corresponding slot formed in theend of said split sleeve.

5. A pan type mixer as claimed in claim 4, including a radiallyextending ange formed on said semi-circular projection :adjacent saidslot formed therein to which said locking key is bolted to retain it inthe locking position.

6. A pan type mixer as claimed in claim 5, in which said sleeve isformed with four slots which are provided by notches arranged in theends thereof adjacent the joints of said sleeve halves.

7. A pan type mixer comprising an :annular pan providing a mixingchamber; a Vertical shaft substantially co axial with said pan; a spiderstructure comprising a p1urality of radially disposed spider armsmounted on said shaft for rotation about the axis thereof above thelevel of material to be mixed in said chamber; a plurality of supportingarms connected to and depending from said spider arms respectively intosaid mixing chamber; a plurality of blades connected to the respectivesupporting arms and being adapted to circulate within said mixingchamber on rotation of said spider structure; and a plurality of Wearresistant sleeves surrounding and being secured to the respecitvesupporting arms and extending between the connections of said supportingarms to said spider arms and the connections of said blades to saidsupporting arms.

8. A pan type mixer according to claim 7 in which said wear resistantsleeves are of tubular formation and are split longitudinally each topresent two sleeve halves; and means for securing said sleeve halves inpairs on said supporting arms.

9. A pan type mixer according to claim 8 including semi-circularprojections on the connections between said supporting arms `and saidspider arms and blades respectively for receiving the ends of saidsleeve halves.

10. A pan type mixer according to claim 9 including locking means forpreventing rotation and thus removal of said sleeve halves, said lockingmeans comprising a locking key passing through a slot formed in one ofsaid semi-circular projections and into a corresponding slot formed inone end of the associated split sleeve.

11. A pan type mixer according to claim 10 including a radiallyextending flange formed on said semi-circular projection adjacent saidslot formed therein and to which flange said locking key is bolted toretain it in locking position.

12. A pan type mixer according to claim 11 in which said sleeve isformed with four slots which are provided by notches arranged in theends thereof adjacent the joints of said sleeve halves.

References Cited by the Examiner UNITED STATES PATENTS 874,252 12/07Schwiete 259--178 2,243,028 5/41 Ball 259-178 2,817,502 12/57 Yohe259--108 CHARLES A. WILLMUTH, Primary Examiner.

7. A PAN TYPE MIXER COMPRISING AN ANNULAR PAN PROVIDING A MIXER CHAMBER;A VERTICAL SHAFT SUBSTANTIALLY COAXIAL WITH SAID PAN; A SPIDER STRUCTURECOMPRISING A PLURALITY OF RADIALLY DISPOSED SPIDER ARMS MOUNTED ON SAIDSHAFT FOR ROTATION AN OUT THE AXIS THEREOF ABOVE THE LEVEL OF MATERIALTO BE MIXED IN SAID CHAMBER; A PLURALITY OF SUPPORTING ARMS CONNECTED TOAND DEPENDING FROM SAID SPIDER ARMS RESPECTIVELY INTO SAID MIXINGCHAMBER; A PLURALITY OF BLADES CONNECTED TO THE RESPECTIVE SUPPORTINGARMS AND BEING ADAPTED TO CIRCULATE WITHIN SAID MIXING CHAMBER ONROTATION OF SAID SPIDER STRUCTURE; AND A PLURALITY OF WEAR RESISTANTSLEEVES SURROUNDING AND BEING SECURED TO THE RESPECTIVE SUPPORTING ARMSAND EXTENDING BETWEEN THE CONENCTIONS OF SAID SUPPORTING ARMS TO SAIDSPIDER ARMS AND THE CONNECTIONS OF SAID BLADES TO SAID SUPPORTING ARMS.